Because of high cost of heating dwelling places, commercial establishments and the like, it has become essential to operate heating units in a more efficient manner to conserve high price fuels. A part of the solution to this problem is the more efficient storage of heat within the burner chamber during burner operation. By storing at least a part of the heat during the periodic burning stages, it is possible to then release at least a part of the heat in a more useful manner. Thus heat can be generated and can be expended in a controlled and therefore more economical fashion.
A major time of heat loss is during the burning operation when temperatures reach their peak and it is at that stage that heat is most likely to be lost to the system. Since, however, it is proposed in the present invention to absorb a greater part of the heat during the heating cycle and then expending the heat in a useful manner, a more efficient utilization is realized in this described manner.
It has been further found, that one of the major sources of heat loss is through the stack. While it appears that one "obvious" way to solve the problem is to provide a valve in the stack which would open during the heating operation and thereafter close, this has not proved to be a very practical way of preventing heat loss because there is heretofore not been devised a practical way of coordinating stack closure and stack opening with burner operation in a manner which could insure the free passage of exhaust gases through the stack during normal burner operation, allow purging of combustion gases after burner operation and then effect closure of the stack. All this must of course be automatic and should occur with unfailing certainty and in addition, effect closure of the flue in the event of power failure and automatic opening thereof when power is restored.
Consequently, the stack is closed, and automatically, except during actual firing and purging of possibly dangerous gases within the combustion chamber.